Joseph-Horne T, Wood P M, Wood C K, Moore A L, Headrick J, Hollomon D
IACR-Long Ashton Research Station, Department of Agricultural Sciences, University of Bristol, Long Ashton, Bristol, BS41 9AF, United Kingdom.
J Biol Chem. 1998 May 1;273(18):11127-33. doi: 10.1074/jbc.273.18.11127.
This article describes the first detailed analysis of mitochondrial electron transfer and oxidative phosphorylation in the pathogenic filamentous fungus, Gaeumannomyces graminis var. tritici. While oxygen consumption was cyanide insensitive, inhibition occurred following treatment with complex III inhibitors and the alternative oxidase inhibitor, salicylhydroxamic acid (SHAM). Similarly, maintenance of a Deltapsi across the mitochondrial inner membrane was unaffected by cyanide but sensitive to antimycin A and SHAM when succinate was added as the respiratory substrate. As a result, ATP synthesis through complex V was demonstrated to be sensitive to these two inhibitors but not to cyanide. Analysis of the cytochrome content of mitochondria indicated the presence of those cytochromes normally associated with electron transport in eukaryotic mitochondria together with a third, b-type heme, exhibiting a dithionite-reduced absorbance maxima at 560 nm and not associated with complex III. Antibodies raised to plant alternative oxidase detected the presence of both the monomeric and dimeric forms of this oxidase. Overall this study demonstrates that a novel respiratory chain utilizing the terminal oxidases, cytochrome c oxidase and alternative oxidase, are present and constitutively active in electron transfer in G. graminis tritici. These results are discussed in relation to current understanding of fungal electron transfer and to the possible contribution of alternative redox centers in ATP synthesis.
本文描述了对致病丝状真菌小麦全蚀病菌（Gaeumannomyces graminis var. tritici）中线粒体电子传递和氧化磷酸化的首次详细分析。虽然氧气消耗对氰化物不敏感，但在用复合体III抑制剂和交替氧化酶抑制剂水杨羟肟酸（SHAM）处理后会发生抑制作用。同样，当以琥珀酸作为呼吸底物时，跨线粒体内膜的膜电位维持不受氰化物影响，但对抗霉素A和SHAM敏感。因此，通过复合体V的ATP合成被证明对这两种抑制剂敏感，而对氰化物不敏感。线粒体细胞色素含量分析表明，存在那些通常与真核生物线粒体电子传递相关的细胞色素，以及第三种b型血红素，其在连二亚硫酸盐还原后在560 nm处有最大吸光度，且与复合体III无关。针对植物交替氧化酶产生的抗体检测到了这种氧化酶的单体和二聚体形式的存在。总体而言，这项研究表明，在小麦全蚀病菌中存在一种利用末端氧化酶细胞色素c氧化酶和交替氧化酶的新型呼吸链，并且在电子传递中组成性地活跃。本文结合当前对真菌电子传递的理解以及交替氧化还原中心在ATP合成中的可能作用对这些结果进行了讨论。
